Concrete Block Calculator
How many standard 8×8×16 concrete blocks (CMU) a wall takes — the count block yards and masons use, with a breakage allowance.
Result
| Wall area | |
| Blocks (exact) |
Units & conversions used
The standard US concrete block is nominally 8 in high × 16 in long (actual 7⅝ × 15⅝ in, laid with a ⅜ in joint). Each block therefore covers 128 in² of wall — 1.125 blocks per square foot. Metric wall dimensions are converted to feet first.
Formula & source
Blocks = wall length(ft) × wall height(ft) × 1.125 × (1 + waste%)
Source: the 1.125 blocks/ft² figure is the standard CMU estimating constant published across masonry references, derived from the nominal 8×16 in block face with mortar joint. Half blocks, bond-beam blocks and lintel blocks are counted separately on real jobs — this calculator gives the field-block count.
Worked example (you can verify by hand)
Input: 20 ft × 8 ft wall, 5% waste.
- Wall area: 20 × 8 = 160 ft²
- Blocks before waste: 160 × 1.125 = 180
- With 5%: 180 × 1.05 = 189
Expected output: 189 blocks to buy.
Limitations — what this cannot do
- Counts standard 8×16 field blocks for a single-wythe wall. Corner, half, bond-beam and lintel units, and any concrete fill (grout) for reinforced cells, are separate line items.
- Openings are not subtracted — deduct window/door areas first, or treat the surplus as cutting stock.
- Block walls that hold back soil or carry loads need engineering (rebar, grout, footing size). This is a material count, not a design. Mortar quantities are in our mortar calculator.
FAQ
How many concrete blocks are on a pallet?
Standard 8×8×16 blocks commonly ship about 90–120 per pallet depending on the plant and block weight. Our example wall (189 blocks) is roughly two pallets — pallet delivery beats loading singles into a pickup.
How much does a concrete block cost?
A standard 8×8×16 CMU commonly sells for about $2–$3.50 each at US home centers and block yards (2025–2026), with lightweight and specialty units higher. Mortar, rebar, grout fill and delivery are separate costs.
How many blocks do I need for a foundation?
Measure the perimeter wall by wall (length × height below and above grade), multiply by 1.125, add waste. Foundations also need grout-filled and reinforced cells per code — the block count from this calculator is your starting line item, not the whole foundation budget.
How much mortar goes with these blocks?
As a rule of thumb, one 80 lb bag of mortar lays about 35 standard blocks. Run your block count through our mortar calculator for the bag count.